How Long Does Tomato Blight Stay in the Soil?

by Renee Rall-Harden

The tomato plant is susceptible to blight diseases.

As a home gardener, you may know the frustration of dealing with tomato blight. After losing some, or all, of your crop to early or late blight or septoria leaf spot, you're keen to avoid the spread of these scourges in the next growing season. Blights are fungal diseases that are spread by spores in foggy, wet conditions. Spores overwinter on tomato and weed refuse in gardening beds, so it is important to rotate your crops to minimize the spread of blight.

Types of Blight

Septoria leaf spot is caused by the fungus Septoria lycopersici, which attacks the lower leaves when the fruits have appeared. Leaves may wilt and die, leading to lower fruit yield, and fruits are more susceptible to sun scald. The Alternaria solani fungus causes early blight, which attacks the lower leaves with brown or black spots, eventually wilting and killing leaves. It can also attack and kill stems and occasionally infects fruits with sunken black spots that often cause the fruits to drop before they are ripe. Late blight is caused by the funguslike Phytophthora infestans. This organism attacks tomato plants during moist, cool weather and appears as dark green or nearly black spots on leaves. Late blight spreads quickly in wet conditions, and spots will soon appear on the fruit.

Fighting Blight

Blight spores can survive in the soil for three or four years. Only plant tomatoes in the same bed every three to four years, and remove and burn tomato refuse in the fall. Throw out and replace young transplants that appear to be in the early stages of fungal infection, and, if blight appears in young plants after transplanting, remove the infected leaves so that the spores do not make their way into the soil. When possible, water at the root, as moist leaves and stems are more vulnerable to fungal disease.

About the Author

Renee Rall-Harden has worked as a writer and editor for more than six years. She has contributed to magazines such as "Ohio Magazine" and online for Pratt & Lambert's Personal Expressions. Rall-Harden holds a Bachelor of Arts in journalism and English from Ashland University.

Photo Credits

Have Feedback?

Thank you for providing feedback to our Editorial staff on this article. Please fill in the following information so we can alert the Home Guides editorial team about a factual or typographical error in this story. All Fields are required.